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The Eocene–Oligocene extinction event, also called the Eocene-Oligocene transition (EOT) or Grande Coupure (French for "great cut"), is the transition between the end of the Eocene and the beginning of the Oligocene, an extinction event and faunal turnover occurring between 33.9 and 33.4 million years ago. [1]
The Eocene-Oligocene Boundary 33.9 million years ago was the transition from the last greenhouse period to the present icehouse climate. [17] [18] [10] At this point, when ~25% more of Antarctica's surface was above sea level and able to support land-based ice sheets relative to today, [19] CO 2 levels had dropped to 750 ppm. [20]
The Eocene-Oligocene transition was a major cooling event and reorganization of the biosphere, [33] [34] being part of a broader trend of global cooling lasting from the Bartonian to the Rupelian. [ 35 ] [ 36 ] The transition is marked by the Oi1 event, an oxygen isotope excursion occurring approximately 33.55 million years ago, [ 37 ] during ...
Following the maximum was a descent into an icehouse climate from the Eocene Optimum to the Eocene–Oligocene transition at 34 Ma. During this decrease, ice began to reappear at the poles, and the Eocene–Oligocene transition is the period of time when the Antarctic ice sheet began to rapidly expand. [52]
The Drake Passage opened 33.9 million years ago (the Eocene-Oligocene transition), severing Antarctica from South America. The Antarctic Circumpolar Current could then flow through it, isolating Antarctica from warm waters and triggering the formation of its huge ice sheets.
[15] [16] The end of the Eocene was marked by the Eocene–Oligocene extinction event, [17] [18] [19] the European face of which is known as the Grande Coupure. [20] [21] The Oligocene Epoch spans from 33.9 million to 23.03 million years ago. The Oligocene featured the expansion of grasslands which had led to many new species to evolve ...
Archaeoceti ("ancient whales"), or Zeuglodontes in older literature, is a paraphyletic group of primitive cetaceans that lived from the Early Eocene to the late Oligocene 1] Representing the earliest cetacean radiation , they include the initial amphibious stages in cetacean evolution , thus are the ancestors of both modern cetacean suborders ...
The late Eocene Epoch saw the rebirth of seasons, which caused the expansion of savanna-like areas with the earliest substantial grasslands. [57] [58] At the transition between the Eocene and Oligocene epochs there was a significant extinction event, the cause of which is debated. The Oligocene Epoch spans from 34 million to 23 million years ago.